New Geophysical Approaches For Providing Hydrogeologists With What They Need:

Transcription

1 New Geophysical Approaches For Providing Hydrogeologists With What They Need: Fracture Flow, Water Content, Hydaulic Conductivity, Groundwater Discharge and Flow Zones HIGH K and T Paul Bauman, Franklin Koch, Rosa La, Alastair McClymont, Randy Shinduke, Landon Woods, Advisian WorleyParsons Elliot Grunewald, Vista Clara WaterTech, April 4,

2 Borehole Logging For Fracture Flow Characterization 28 mbgs Interpreted structure: Includes orientation and aperture Imaged fracture Fracture aperture Temperature & fluid conductivity changes indicate flow 32 mbgs But What About Porous Media?

3 Objectives Are to Show: DTS can identify the movement of groundwater into surface water A similar approach combined with borehole geophysics, taken in a borehole in high porosity (θ) and high permeability (K) porous media, can identify discrete zones of groundwater movement. DTS cable along a creek Presentation Title April 13, 2017 Page 3 DTS cable in a borehole

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6 South 2 km DTS Profiles Over 5 Months Distance (m) July (16 to 21 o C) no seepage no groundwater discharge North Temperature ( o C) September (9 to 14 o C) October (6 to 11 o C) November (-2 to 3 o C) seepage groundwater discharge very minor seepage seepage 0 m 1900 m NO EVIDENCE

7 Relief Plot of June 2015 DTS Data Along 2 km Reach Northing

8 Normalized DTS Temperatures During The Month Of July, 2015 Horizontal banding responding to diurnal changes Vertical banding responding to groundwater discharge of cooler groundwater into warmer surface water Vertical temperature anomalies due to expose cable 0 Distance (m) Time (hr) 0 exposed cable

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11 Water table NMR Determination Of Hydraulic Conductivity Borehole Resolution 0.5m Depth (m) THE SCHLUMBERGER DOLL RESEARCH (SDR) EQUATION THE SQUARED MEAN-OF- ECHOES (SOE) EQUATION The SOE is strongly weighted by the longest relaxation time, and therefore may be preferable in high porosity waste rock. Water content Hydraulic conductivity

12 Setup For A Single Borehole Heat Tracer Test Utilizing DTS Heating Cable WELL DTS Cable 6 FULLY SCREENED PVC CASING Heating Cable On Groundwater Flow Temperature Off Three individual temperature measurements along DTS cable 0 t o Time t end Two cables are coupled a small fixed (4 cm) distance apart

13 Transmissivity Measurements With Downhole DTS Time elapsed (min) Depth (meters below ground surface) WATER TABLE AT 50 mbgs

14 Measured Temperature Variation Utilizing Distributed Temperature Sensing (DTS) in Time elapsed (min) Depth (meters below ground surface) Water Table AT 50 mbgs 59 mbgs 69 mbgs 72 mbgs (DTS measured temperature minus background temperature) The borehole is screened throughout the entire length Background temperature recorded from 0 to 35 minutes High flow zones identified by slow heating and rapid cooling Borehole was heated from 35 to 185 minutes Borehole was cooling from 185 to 245 minutes

15 48 60 GAMMA cps TEMPERATURE C DIFFERENTIAL TEMPERATURE FLUID CONDUCTIVITY TEMP Continuous DTS Profiles Plotted As Temperature Difference 0 DEGREE C 2 59 mbgs Well mbgs Interval of flow based on DTS tracer test and temperature logs O Temperature C TEMP.08 TEMP 69 mbgs mbgs 84 DTS Measurements Done Continually Averaged Over 1 Minute 118 mbgs

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18 FLUID EC TEMP m 3 /day 30 m 3 /day 72 mbgs 59 mbgs 69 mbgs 53.5 mbgs 60.5 mbgs 65.5 mbgs 70 mbgs 75 mbgs Spinner Flow Meter Data Show That All Injected Water Enters the Waste Rock Between the Water Table and 75 mbgs SPINNER FLOWMETER LOGS NO FLOW 4 UP LOGS AND 4 DOWN SPINNER LOGS WERE RUN AT VARYING VELOCITIES DURING TRACER TEST

19 Cross-hole ERT Tracer Test

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21 CROSS-WELL ERT SURVEY 5 m 10 m 5 m electrode spacing, 10 m spacing between boreholes Inversion includes both single well dipole-dipole and cross-well data sets Water table sample in-hole measurement A B M 9 electrodes in and 10 electrodes in active N A M B N Sample cross-hole measurement Electrodes above water table and at depth not used so as to speed acquisition Survey repeated every 2.5 minutes ERT survey ended 35 minutes after injection

22 Background minus post-injection Resistivity in Ohm-m TRACER TEST RESISTIVITY TOMOGRAPHY, 15 MINUTES AFTER INJECTION COMPLETE A positive resistivity anomaly of about 1 ohm-m (2% to 3%) is observed from 54 mbgs to 71

23 Results correlate well with DTS, Temperature, fluid conductivity and spinner flow meter data. Formation/ Fluid/ERT Cond. Temp/ ΔTemp DTS Spinner flowmeter ERT

24 CONCLUSION: 50 mbgs 72 mbgs NO FLOW DTS, when combined with other geophysical techniques, can offer an intuitive and inexpensive, and perhaps semi-quantitative means of monitoring water movement in boreholes DTS surveys in surface water and boreholes suggest that conventional hydrogeological determinations of groundwater discharge zones in surface water, and flow in aquifers may be oversimplified